The present invention relates to a flashing device for cameras, and more particularly, to controlling a charging of condenser for supplying electricity to a light emiiting member.
A flashing device can emit light at a specified voltage (hereinafter referred to as a first voltage), however, it is desirable to apply a voltage (hereinafter referred to as the second voltage), which is higher than the first voltage to the light emitting device, in order to obtain the maximum luminous energy of the flashing device.
Conventionally, charging of a condenser for supplying voltage to the light emitting device is performed through a voltage increasing circuit which is connected with a power source. With this construction, when the recharging of the condenser to the second voltage (hereinafter referred to as a full charge) and light emission of the light emitting device are successively repeated, elements such as transistors or a transformer in the voltage increasing circuit are undesirably heated and the voltage increasing circuit may be burnt or damaged.
Therefore, in order to prevent such problems, a device is provided with a sensor device for detecting the temperature of the voltage increasing circuit, and the recharge of the condenser is prohibitted when the temperature of the voltage increasing circuit is relatively high. Alternatively, a device is suggested in which recharging is prohibited for a predetermined period of time after charging has been finished or flash light has been emitted.
In the former case, however, the sensor device occupies space. Therefor, the entire flashing device becomes large in size.
In the latter case, in order to allow the flash light emission and full charge to be repeatedly performed, a recharge prohibit period should be specified for a sufficiently long period so that the voltage increasing circuit is not undesirablly heated.
If the recharge prohibit period is specified for a long time, however, there may arises a problem that the flash light emission can not be used immediately after the light emission, and promptness of the flashing device become lowered.